using System;
using System.Collections;

using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Math;

namespace Org.BouncyCastle.Asn1.CryptoPro
{
	public class Gost3410ParamSetParameters
		: Asn1Encodable
	{
		private readonly int keySize;
		private readonly DerInteger	p, q, a;

		public static Gost3410ParamSetParameters GetInstance(
			Asn1TaggedObject	obj,
			bool				explicitly)
		{
			return GetInstance(Asn1Sequence.GetInstance(obj, explicitly));
		}

		public static Gost3410ParamSetParameters GetInstance(
			object obj)
		{
			if (obj == null || obj is Gost3410ParamSetParameters)
			{
				return (Gost3410ParamSetParameters) obj;
			}

			if (obj is Asn1Sequence)
			{
				return new Gost3410ParamSetParameters((Asn1Sequence) obj);
			}

			throw new ArgumentException("Invalid GOST3410Parameter: " + obj.GetType().Name);
		}

		public Gost3410ParamSetParameters(
			int			keySize,
			BigInteger	p,
			BigInteger	q,
			BigInteger	a)
		{
			this.keySize = keySize;
			this.p = new DerInteger(p);
			this.q = new DerInteger(q);
			this.a = new DerInteger(a);
		}

		private Gost3410ParamSetParameters(
			Asn1Sequence seq)
		{
			if (seq.Count != 4)
				throw new ArgumentException("Wrong number of elements in sequence", "seq");

			this.keySize = DerInteger.GetInstance(seq[0]).Value.IntValue;
			this.p = DerInteger.GetInstance(seq[1]);
			this.q = DerInteger.GetInstance(seq[2]);
			this.a = DerInteger.GetInstance(seq[3]);
		}

		public int KeySize
		{
			get { return keySize; }
		}

		public BigInteger P
		{
			get { return p.PositiveValue; }
		}

		public BigInteger Q
		{
			get { return q.PositiveValue; }
		}

		public BigInteger A
		{
			get { return a.PositiveValue; }
		}

		public override Asn1Object ToAsn1Object()
		{
			return new DerSequence(new DerInteger(keySize), p, q, a);
		}
	}
}
